A substance comprising a steel bombshell and a burster or a chemical agent contained in the interior is known as ammunition (a cannonball, a bomb, a land mine, a sea mine, etc.) for military use.
As a method for treating such ammunition, a method of supplying the explosion energy of an explosive to ammunition in a sealable pressure vessel and thereby detonating a burster while a bombshell is destroyed is known. As the pressure vessel, a sufficiently robust vessel capable of enduring a high pressure generated inside the pressure vessel by the explosion of an explosive is used. The treatment method by detonation does not require dismantling work and hence can be applied to the treatment of not only well-preserved weapons but also weapons having been hardly disassemblable by aging deterioration, deformation, or the like. Moreover, in the case of treating a bomb having a chemical agent harmful to a human body, it has the advantage that almost all of the chemical agent can be decomposed without scattering the chemical agent in the atmosphere by creating an ultrahigh temperature field and an ultrahigh pressure field caused by the explosion of an explosive in a pressure vessel.
Such a treatment method is disclosed in Patent Literature 1 for example. The method of Patent Literature 1: includes, in a sealable pressure vessel, a step of placing an ANFO explosive around an object to be treated (hereinafter simply referred to as “an object” or “the object”) and wrapping the ANFO explosive with a sheet-shaped explosive and a process of initiating explosion at a prescribed end of the sheet-shaped explosive, sequentially detonating the sheet-shaped explosive in a prescribed direction, and sequentially detonating the ANFO explosive in the prescribed direction in accordance with the detonation of the sheet-shaped explosive; thereby making it possible to supply the detonation energy of the ANFO explosive to the object to be treated and thereby blast the object while the burster is detonated.
As the design standard of a pressure vessel used for a blast treatment, the same standard as an ordinary static pressure vessel (a vessel subject to a high pressure for a long period of time) is used. Specifically, the pressure vessel is designed so that at least a primary stress generated at a structural part (a part excluding a local structural discontinuous part of the pressure vessel) may not exceed an elastic region when a load is applied. In other words, a load applied to the pressure vessel is set so that a primary stress generated at the structural part of the pressure vessel may fall within an elastic region.
A blast treatment using a pressure vessel as stated above is required to treat an object safely and reliably. Specifically, energy given to an object is required to be increased while a pressure vessel is prevented from giving excessive plastic deformation and being broken when the object is blasted. To enlarge the size of a pressure vessel and increase the elastic limit load of the pressure vessel for that purpose however causes the cost and the necessary space to increase conspicuously.